Fuel Supply Device for Internal Combustion Engine

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2024-045367, filed on Mar. 21, 2024, the entire contents of which are incorporated herein by reference.

The present disclosure relates to a fuel supply device for an internal combustion engine.

For example, an internal combustion engine disclosed in Japanese Laid-Open Patent Publication No. 2022-182969 reduces the pressure of gas fuel stored in a tank before supplying the gas fuel to fuel injection valves.

As a method of fuel pressure control such as the one described above, the following control can be implemented.

Specifically, an electromagnetic valve is provided in a fuel passage that connects a tank for storing fuel to a fuel injection valve that supplies fuel to a cylinder. The electromagnetic valve opens and closes the fuel passage. An allowable upper limit value and an allowable lower limit value are set for the target of the fuel pressure. When fuel injection from the fuel injection valve is performed in a state in which the electromagnetic valve is closed, fuel flows out from the fuel passage downstream of the electromagnetic valve. As a result, the fuel pressure downstream of the electromagnetic valve decreases. When the downstream fuel pressure reaches the lower limit value, the electromagnetic valve is driven to open. This allows fuel to be supplied to the fuel passage downstream of the electromagnetic valve. Consequently, the fuel pressure downstream of the electromagnetic valve increases. When the downstream fuel pressure reaches the upper limit value, the electromagnetic valve is driven to close. By repeatedly driving the electromagnetic valve to open and close in this manner, the pressure of the fuel downstream of the electromagnetic valve, which is the pressure of the fuel supplied to the fuel injection valve, is adjusted to a fuel pressure within a range defined by the upper limit value and the lower limit value.

When performing fuel pressure control that involves repeated opening and closing of the electromagnetic valve, wear may progress in sliding parts of the electromagnetic valve or similar components due to the repeated opening and closing operations during the execution of fuel pressure control.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one general aspect, a fuel supply device for an internal combustion engine includes a tank that stores fuel, a fuel injection valve that supplies fuel to a cylinder, a fuel passage that supplies the fuel in the tank to the fuel injection valve, an electromagnetic valve that is provided in the fuel passage so as to open and close the fuel passage, a temperature increasing mechanism that increases a temperature of an inflow fuel that is fuel flowing into the electromagnetic valve, and a processing circuitry that executes a fuel pressure control. In the fuel pressure control, the electromagnetic valve is repeatedly opened and closed such that a fuel pressure in a section of the fuel passage connected to a downstream side of the electromagnetic valve in a flow direction of the fuel in the fuel passage is controlled, and that a fuel pressure in the fuel passage falls within a range defined by an upper limit value and a lower limit value. The processing circuitry is configured to execute a temperature increasing process that operates the temperature increasing mechanism to increase the temperature of the inflow fuel during execution of the fuel pressure control.

Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.

Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted.

Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art.

In this specification, “at least one of A and B” should be understood to mean “only A, only B, or both A and B.”

A fuel supply devicefor an internal combustion engineaccording to an embodiment will now be described with reference to.

The internal combustion engineshown inis mounted on a vehicle, and uses hydrogen gas, which is gas fuel, as fuel.

A throttle valvethat adjusts an intake air amount is provided in an intake passageof the internal combustion engine.

A fuel supply deviceincluded in the internal combustion engineincludes fuel injection valves, a tank, a fuel pipe, a first shut-off valve, a second shut-off valve, a pressure reducing valve, a delivery pipe, and a temperature increasing mechanism.

The fuel injection valvessupply fuel to cylindersof the engine.

The tankstores hydrogen gas, which is gas fuel, in a high-pressure compressed state.

The fuel pipeconnects the tankand the delivery pipe.

The fuel injection valvesare connected to the delivery pipe. The fuel pipeand the delivery pipeare a fuel passage connecting the tankand the fuel injection valves. The hydrogen gas stored in the tankis supplied to the fuel injection valvesvia the fuel pipeand the delivery pipe.

The first shut-off valve, the pressure reducing valve, and the second shut-off valveare arranged in the fuel pipein this order in a direction of fuel flow.

The first shut-off valveis an electromagnetic valve arranged near an outlet of the tank. When the first shut-off valveis open, fuel is supplied from the tankto the fuel pipe. When the first shut-off valveis closed, the supply of fuel from the tankto the fuel pipeis stopped.

The pressure reducing valvedecompresses the high-pressure hydrogen gas stored in the tankto a predetermined level (for example, about 4 MPa), and supplies the decompressed hydrogen gas to the fuel injection valves.

The second shut-off valveis an electromagnetic valve that opens and closes the fuel passage, and is disposed near the delivery pipein the fuel passage. When the second shut-off valveis opened by energization, fuel is supplied to the delivery pipe. When the second shut-off valveis closed due to the de-energization, the supply of fuel to the delivery pipeis stopped.

The first shut-off valveand the second shut-off valveare closed while the operation of the internal combustion engineis stopped. On the other hand, the first shut-off valveand the second shut-off valveare basically open during operation of the internal combustion engine.

The first pressure sensoris provided in the fuel pipebetween the first shut-off valveand the pressure reducing valve. The first pressure sensordetects a first pressure Pwhich is a fuel pressure in the fuel pipebetween the first shut-off valveand the pressure reducing valve.

The second pressure sensorprovided in the fuel pipebetween the pressure reducing valveand the second shut-off valvedetects a second pressure Pthat is the fuel pressure in the fuel pipebetween the pressure reducing valveand the second shut-off valve.

A third pressure sensorprovided in the delivery pipedetects a third pressure P, which is a fuel pressure in the delivery pipe. A temperature sensorprovided in the delivery pipedetects a fuel temperature THF which is the temperature of the fuel in the delivery pipe.

The fuel supply system of the internal combustion engineis provided with a temperature increasing mechanismwhich increases the temperature of the inflow fuel which is the fuel which flows into the second shut-off valve. The fuel passage connected to the upstream side of the second shut-off valvein the flow direction of the fuel in the fuel passage is referred to as an upstream-side fuel passage. The upstream-side fuel passage of the present embodiment includes an upstream-side fuel pipewhich is a fuel pipe connecting the pressure reducing valveand the second shut-off valve.

The temperature increasing mechanismincludes a pipe, a first electromagnetic valve, and a second electromagnetic valve. The first electromagnetic valveis provided at a connection portion between the pipeand the upstream-side fuel pipe. The second electromagnetic valveis provided at a connection portion between the pipeand the upstream-side fuel pipeand at a portion downstream of the first electromagnetic valve.

The pipeis connected in parallel to the upstream-side fuel pipe. A part of the pipeis disposed so as to pass through the vicinity of a high-temperature portion of the internal combustion engine, which is a heat source. Therefore, the fuel heated by the heat source flows through the pipe. Examples of the high-temperature portion of the internal combustion engineinclude a cylinder block and a cylinder head.

The first electromagnetic valveand the second electromagnetic valveare operation valves that regulate a flow connection state between the upstream-side fuel pipeand the pipe. The first electromagnetic valveis provided at a connection portion between one of both ends of the pipeand the upstream-side fuel pipe. The second electromagnetic valveis provided at a connection portion between the other end portion of the pipeand the upstream-side fuel pipe.

When the operation positions of the valve bodies of the first electromagnetic valveand the second electromagnetic valveare set to the first mode, the communication between the upstream-side fuel pipeand the pipeis blocked. Therefore, in the first mode, the fuel that has received heat from the heat source does not flow into the upstream-side fuel pipe. On the other hand, when the operation positions of the valve bodies of the first electromagnetic valveand the second electromagnetic valveare set to the second mode, the upstream-side fuel pipeand the pipecommunicate with each other. Therefore, in the second mode, the fuel that has received heat from the heat source flows into the upstream-side fuel pipe.

The controllerperforms various controls such as fuel injection of the internal combustion engineby controlling various control targets such as the throttle valve, the fuel injection valves, the first shut-off valve, the second shut-off valve, the first electromagnetic valve, and the second electromagnetic valve. The controllerincludes a CPUand a memoryconstituted by a ROM, a RAM, and the like. The CPUexecutes a program stored in the memoryto perform various controls.

The controllerrefers to various values used to control the internal combustion engine. For example, the controllerrefers to detection values of the first pressure sensor, the second pressure sensor, the third pressure sensor, and the temperature sensor. Further, the controllerrefers to a detection signal of an accelerator position sensorthat detects an accelerator operation amount ACCP that is an operation amount of an accelerator pedaloperated by a driver of the vehicle on which the internal combustion engineis mounted. In addition, the controllerrefers to a detection signal of a speed sensorthat detects a vehicle speed SP of a vehicle on which the internal combustion engineis mounted. Further, the controllerrefers to a detection signal of an air flow meterthat detects an intake air amount GA of the internal combustion engine, and a detection signal Scr of a crank angle sensorthat detects a rotation angle of a crankshaft of the internal combustion engine.

The controllercalculates the engine rotation speed NE based on the detection signal Scr of the crank angle sensor. In addition, the controllercalculates an engine load factor KL based on the engine rotation speed NE and the intake air amount GA. The engine load factor KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount at the time of steady operation of the internal combustion enginein a full load state at the current engine rotation speed NE. The cylinder inflow air amount is the amount of air that flows into each cylinder in the intake stroke.

Hydrogen gas, which serves as the engine fuel, has a wider range of combustible air-fuel mixtures compared to gasoline and can burn even with a relatively lean air-fuel mixture. Therefore, the controlleradjusts the output of the internal combustion enginethrough the following combustion control.

That is, the controllercalculates a requested output Pe, which is a requested value of the engine output of the internal combustion engine, based on the accelerator operation amount ACCP and the like. The controllersets the requested injection amount Qd based on the requested output Pe. The requested injection amount Qd is a target value of the fuel injected from one fuel injection valvein one combustion cycle. Based on the target air-fuel ratio AFt and the requested injection amount Qd, the controllercalculates a requested air amount GAd that is a target value of the intake air amount requested for obtaining the target air-fuel ratio AFt. The target air-fuel ratio AFt of the present embodiment is a lean air-fuel ratio such as an excess air ratio λ=2.5 to 3.0, for example. Then, the controllercontrols the fuel injection valvessuch that an amount of fuel corresponding to the requested injection amount Qd is injected. Further, the controllercontrols the opening degree of the throttle valveso that an amount of air corresponding to the requested air amount GAd is introduced into the cylinder. In this way, in the internal combustion engine, the output adjustment is performed by changing the air-fuel ratio of the air-fuel mixture through the adjustment of the fuel injection amount and the intake air amount.

The controllerexecutes fuel pressure control for controlling the pressure of the fuel supplied to the fuel injection valves, that is, the fuel pressure in the fuel passage connected to the downstream side of the second shut-off valve. In the fuel pressure control, the second shut-off valveis repeatedly opened and closed so that the fuel pressure in the fuel passage connected to the downstream side of the second shut-off valvebecomes a pressure within the control range CR defined by an upper limit value PtU and a lower limit value PtL. A target fuel pressure Pt in the fuel pressure control is lower than the second pressure P, which is the fuel pressure reduced by the pressure reducing valve, and is set in advance. For example, the target pressure Pt is about 1 Mpa. An upper limit value of the fuel pressure allowable with respect to the target pressure Pt is set to an upper limit value PtU. Further, a lower limit value of the fuel pressure allowable with respect to the target pressure Pt is set to a lower limit value PtL.

shows an example of fuel pressure control. Part (a) ofshows the changes in the third pressure P, and part (b) ofshows the operating states of the second shut-off valve.

Before a point in time t, the hybrid vehicle is traveling normally, and the second shut-off valveis maintained in the open state. The third pressure Pis equal to the second pressure P, which has been reduced by the pressure reducing valve.

At the point in time t, when the internal combustion engineis requested to be operated at idle, the second shut-off valveis closed and the closed state is maintained. While the second shut-off valveis closed, the amount of fuel in the delivery pipedecreases each time fuel is injected from the fuel injection valves. Therefore, the third pressure Pgradually decreases.

At a point in time t, when the third pressure Preaches the lower limit value PtL, the second shut-off valveis opened. Thus, the fuel is supplied to the fuel passage downstream of the second shut-off valve. Therefore, the fuel pressure downstream of the second shut-off valveincreases. The second shut-off valveis closed when the third pressure Preaches the upper limit values PtU. By repeatedly opening and closing the second shut-off valvein this way, the pressure of the fuel downstream of the second shut-off valveand supplied to the fuel injection valvesis adjusted to a pressure within the control range CR defined by the upper limit value PtU and the lower limit value PtL.

As described above, when the requested injection amount Qd decreases, for example, during idling, the fuel injection control is performed to maintain the third pressure Pat a low level, so that a small amount of fuel is injected from the fuel injection valveswith high accuracy.

When the execution request of the fuel pressure control is not present at a point in time t, the second shut-off valveis maintained in the open state. While the second shut-off valveis open, fuel is supplied from the tanktoward the delivery pipe. Therefore, the third pressure Pgradually increases toward the second pressure P.

When the fuel pressure control, in which the second shut-off valveis repeatedly opened and closed, is executed, there is a possibility that wear progresses in a sliding portion or the like of the second shut-off valvealong with the opening and closing operation during the execution of the fuel pressure control. Further, the electromagnetic coil of the second shut-off valvemay generate heat due to the opening and closing operation during the fuel pressure control. In order to suppress the occurrence of such a disadvantage, the controllerexecutes a temperature increasing process of operating the temperature increasing mechanismsuch that the temperature of the fuel flowing into the second shut-off valveis increased during the execution of the fuel pressure control. Hereinafter, the fuel flowing into the second shut-off valveis referred to as inflow fuel.

shows a procedure of the temperature increasing process executed by the controller. In the process shown in, a program stored in the memoryof the controlleris executed by the CPU. The process shown inis started when the execution of the fuel pressure control is requested. The execution request of the fuel pressure control is requested, for example, when the operation state of the internal combustion engineshifts to an idle operation state. In the following description, the number of each step is represented by the letter S followed by a numeral.

When this process is started, the controllerdetermines whether the third pressure Pis less than or equal to the lower limit value PtL (S). Then, the controllerrepeatedly executes the processing of Suntil it is determined that the third pressure Pis less than or equal to the lower limit value PtL.

When it is determined that the third pressure Pis less than or equal to the lower limit value PtL (S: YES), the controlleroperates the first electromagnetic valveand the second electromagnetic valveto set the second mode (S). When the first electromagnetic valveand the second electromagnetic valveare set to the second mode, the upstream-side fuel pipeand the pipeare in a flow connection state. Therefore, the fuel that has received heat from the internal combustion engine, which is a heat source, flows into the upstream-side fuel pipe, and the temperature of the fuel flowing into the second shut-off valveis increased.